Methods of Studying Cells

Question 1

What are Microscopes?

Answer 1

Microscopes are instruments that produce a magnified image of an object.

Question 2

What is the resolution of a Microscope?

Answer 2

The resolution or resolving power of a microscope is the minimum distance apart that two objects can be in order for them to appear as separate items.

Question 3

What is Cell Fractionation?

Answer 3

Cell fractionation is the process where cells are broken up and the different organelles they contain are separated out.

Question 4

Why is the tissue placed in a cold, buffered solution of the same tissue before fractionation?

Answer 4

Cold- reduce enzyme activity that break down organelles.
Same Water Potential (isotonic) - prevent organelles bursting or shrinking as a result of osmosis.
Buffered - so pH does not fluctuate. A change in pH could alter the structure of organelles or affect enzyme function.

Question 5

What is the homogenation process of cell fractionation?

Answer 5

Cells are broken up by homogenising to release organelles from the cell. The resultant homogenate fluid is filtered to remove complete cells and debris.

Question 6

What is Ultracentrifugation?

Answer 6

The process by which cell fragments of the homogenate are separated in a centrifuge machine.

Question 7

What is the ultracentrifugation process?

Answer 7

• Tube of filtrate is spun at a low speed in centrifuge.
• Nuclei (heaviest organelles) form a pellet in the bottom
• Supernatant (fluid above) is removed leaving the pellet
• Supernatant is spun at a slightly faster speed.
• Mitochondria (next heaviest organelles) pellet.
• The process is repeated, spun faster each time.